Conventionally, an auto-steering control guides an own vehicle to travel on a target travel path by setting a target point based on an image of a traveling road in front from a camera on the own vehicle, and by determining the target travel path to lead to the target point.
However, the setting of the target point in the above-described technique may be hindered when the own vehicle comes close to a lead vehicle. That is, when the own vehicle comes close to the lead vehicle, the traveling road in front of the own vehicle is covered by the lead vehicle. Thus the traveling road is not sufficiently captured by the camera as an image, making it difficult to set the target point.
Thus, to resolve such a problem, a technique disclosed, for example, in a patent document, JP 2005-332192 A (patent document 1) uses an auto-steering control that controls the own vehicle to follow the lead vehicle, when the own vehicle comes close to the lead vehicle. More practically, the technique in patent document 1 sets the target travel path to lead to the position of the lead vehicle, which is set as the target point, for guiding the own vehicle by the auto-steering to travel on the target travel path when the own vehicle comes close to the lead vehicle.
However, the technique in the patent document 1 guides the own vehicle to follow the lead vehicle, even when the lead vehicle crosses a traffic lane boundary to an opposite traffic lane. This means that the own vehicle also crosses the traffic lane boundary to move into and travel in the opposite traffic lane at an unexpected timing of an occupant in the own vehicle, which may frighten the occupant. Further, as a result of crossing the traffic lane boundary to move into the opposite traffic lane, the own vehicle may come close to the on-coming vehicle, which may also frighten the occupant of the own vehicle.